Flora of Clark Valley Area
Flora of Clark Valley Area
This checklist is a start at a flora of the Clark Valley Area. It consists of 157 taxa. Of those 157 taxa, we observed 121 in five different field surveys, and 110 of the 157 taxa have been vouchered here.
The checklist is current as of 11 February 2020, but the following text is from a previous version of this page done in the year 2008.
The floristic area denoted as the Clark Valley Area is delineated by the region outlined in red in the following map:
Only a single road traverses this area, the Rockhouse Canyon Road, on the western side of the Valley (see map below). There is also a private road that accesses private land on the north side of Clark Lake.
The western boundary of this area is the ridgeline / drainage divide of Coyote Mountain and its extension northward, to include the entire drainage basin of Butler Canyon / Rockhouse Canyon up to the San Diego County border with Riverside County.
The eastern boundary is mostly at the 3000 foot elevation contour of the Santa Rosa Mountains. The southeastern boundary is placed just a bit to the west of the Villager Peak Trail and Rattlesnake Canyon, since those two areas are more naturally included in the neighboring floristic area.
The southern boundary is set along Highway S22 to divide Clark Valley from the Badlands. Although this boundary is somewhat arbitrary, S22 gives a well-defined boundary.
For more information about Clark Valley, including pictures from our surveys, see Borrego Desert: Clark Valley.
The voucher search was redone on 24 December 2016. This time only vouchers from Clark Valley itself and the immediately-surrounding areas were accepted. The following text has not been changed from the previous search.
The vouchers come from a search on 8 December 2008 of the Consortium of California Herbaria. The Consortium records were searched for San Diego County specimens that contained the word Clark in the locality (297 vouchers), as well as records with coordinates that fell within a rectangle that encompassed this area (369 vouchers). Duplicate vouchers, vouchers outside this area, and vouchers determined only to the genus that had more than one possible species, were removed.
This process yielded a total of 226 vouchers of 133 unique taxa.
The dominant collectors in the Consortium records were Larry Hendrickson and Kim Marsden and vice-versa, 83 vouchers; R. Mitchel Beauchamp, R. C. Pierce, 71 vouchers; and Bill Sullivan, 31 vouchers. These three sets of collectors accounted for 185 of the 226 vouchers, 82% of the total.
The locations of the vouchers are plotted in the following map, which also shows the boundaries of this region in more detail:
Because many vouchers share the same location, there are far fewer than 226 points plotted above.
Field work has been added from 3/7/09, 12/19/09, and 12/27/16, but the following text has not yet been updated.
Three different areas within the Clark Valley area have been field surveyed. On 27 December 2007, James Dillane, Wayne Armstrong and I surveyed the 2.7 miles of the Alcoholic Pass Trail on Coyote Mountain that are on the Clark Valley side. We surveyed only for species not previously found on the southwestern side of the trail, so this survey was very incomplete. That portion of the trail is shown in green on the following map:
On 9 and 12 December 2008, Mike Crouse and I surveyed the two different routes shown in the following map :
We surveyed 5.75 unique miles on 9 December 2008, and 5.7 unique miles on 12 December 2008.
We also scanned the slopes of the nearby portion of the Santa Rosa Mountains for the elephant trees, Bursera microphylla, reported from that location (indicated by the labeled line in the above map), without finding them. However, since those trees were likely to be leafless at that time, they easily could have escaped our binocular survey from afar. This species was added to the checklist below based on sightings by Mark Jorgensen and Larry Hendrickson.
Note added 30 December 2016: We relocated the elephant trees on 19 December 2009 and vouchered one of them; see The Elephant Trees of Clark Valley.
A total of 63 taxa that could be fairly-confidently identified were found in those three December searches; 19 of those 63 taxa, 30%, are not among the vouchered species. A small number of additional taxa were found that could not be confidently identified at those times.
The unvouchered species do not come from any general problem with my identifications, since those unvouchered species include such easy-to-recognize taxa as Opuntia ramosissima, Psorothamnus spinosus, Ferocactus cylindraceus, and Encelia farinosa. This simply reflects the lack of botanical work for this area. It is possible that one or two of the unvouchered species might be misdetermined, since some of those determinations were made from dead plants.
The total number of taxa presented below is 153, 148 of which are native. Of the 153 taxa, 63 were observed on one of the three field surveys, leaving 90 to be found from surveys at a more optimal time of year, or in locations not yet surveyed. Since 30% of the observed taxa are so far unvouchered, this may imply that the voucher list is on the order of 30% incomplete. However, since many of the unvouchered taxa are common, it may only imply that the most common taxa have not yet been vouchered.
Another source of incompleteness for this checklist is that most of the area has never been surveyed, especially the steep lower slopes of the Santa Rosa Mountains which may defy further surveys indefinitely. I estimate at most 24 square miles (62 km2) has had any survey within it, whereas 34 square miles (88 km2) has never had any survey within it. Using the standard relationship that the number of species scales as the 0.3 power of the area, this implies that (58/24)0.3 = 1.30 times more species should be found in the total area of ~58 square miles. This incompleteness is an additional factor to the incompleteness of the surveyed areas.
Thus the checklist below may be on the order of 1 / 1.32 ~ 60% complete, implying that the true number of taxa in this area might be roughly 260 instead of the 153 present below.
Checklist for the Clark Valley Area
This checklist is current as of 11 February 2020.
This checklist is only for a subset of the Clark Valley Floristic Area defined above, of just the floor of the Valley and the immediately-adjacent areas. Rockhouse Canyon / Butler Canyon has its own flora since that area is very different floristically from the desert floor area.
- Notes on the Scientific Names Used At This Site and
- Information about the order in which the species are presented, and the links from the Scientific Name and Common Name.
An asterisk before the common name indicates a non-native species.
The column with header #Pls gives the minimum number of observed plants from all the surveys in this area, up to a maximum of 99 plants. An x indicates we have observed that taxon but no abundance estimate was made. A V in this column indicates a species that was vouchered in this area that we haven't yet seen. An iN in this column indicates a species with an iNat observation as of 11 February 2020 that we haven't seen and that hasn't been vouchered. A FC in this column indicates a species on Fred Melgert and Carla Hoegen's plant list for this area for 11 February 2020 that wasn't seen, vouchered, or at iNat.
One species, Helianthus niveus ssp. tephrodes, has nr in this column since it may or may not be present in this area, but has been vouchered near this area. One voucher from 1933 has a vague location of North Borrego Valley on road to Clark Lake. Another voucher is from just east of this area on S22.
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# Fam Scientific Name (*)Common Name #Pls Ferns 1 Pte Cheilanthes parryi woolly lipfern 10 Eudicots 2 Aca Justicia californica chuparosa x 3 Ama Amaranthus blitoides *mat amaranth 20 4 Ama Amaranthus fimbriatus fringed amaranth V 5 Ama Tidestromia suffruticosa var. oblongifolia Arizona honeysweet 15 6 Apo Asclepias subulata rush milkweed 2 7 Apo Funastrum hirtellum rambling milkweed V 8 Apo Pilostyles thurberi Thurber's pilostyles 1 9 Ast Ambrosia dumosa burroweed 99 10 Ast Ambrosia salsola var. salsola cheesebush 5 11 Ast Baileya pauciradiata Colorado Desert marigold 79 12 Ast Bebbia juncea var. aspera sweetbush 4 13 Ast Calycoseris parryi yellow tackstem V 14 Ast Calycoseris wrightii white tackstem V 15 Ast Chaenactis carphoclinia var. carphoclinia pebble pincushion V 16 Ast Chaenactis fremontii Fremont pincushion 20 17 Ast Chaenactis stevioides desert pincushion 99 18 Ast Dicoria canescens desert dicoria 20 19 Ast Encelia farinosa brittlebush 20 20 Ast Encelia farinosa var. farinosa brittlebush iN 21 Ast Encelia farinosa var. phenicodonta purple disk flower brittlebush iN 22 Ast Encelia frutescens button encelia 2 23 Ast Geraea canescens hairy desert-sunflower 99 24 Ast Helianthus niveus ssp. tephrodes Algodones Dunes sunflower nr 25 Ast Helianthus petiolaris ssp. canescens gray desert sunflower V 26 Ast Isocoma acradenia var. acradenia entire-leaved alkali goldenbush V 27 Ast Isocoma acradenia var. eremophila toothed-leaved alkali goldenbush 99 28 Ast Lactuca serriola *prickly lettuce FC 29 Ast Lepidospartum squamatum scale-broom V 30 Ast Logfia arizonica Arizona herba impia iN 31 Ast Logfia depressa dwarf filago FC 32 Ast Malacothrix glabrata desert dandelion 30 33 Ast Monoptilon bellioides desert star x 34 Ast Palafoxia arida var. arida Spanish needle 40 35 Ast Pectis papposa var. papposa chinch-weed iN 36 Ast Perityle emoryi Emory's rock-daisy V 37 Ast Peucephyllum schottii pygmy-cedar x 38 Ast Pluchea sericea arrow-weed 99 39 Ast Psathyrotes ramosissima turtleback x 40 Ast Rafinesquia neomexicana desert chicory 99 41 Ast Senecio mohavensis Mojave ragwort iN 42 Ast Stephanomeria exigua ssp. exigua slender wreathplant V 43 Ast Stephanomeria pauciflora wire-lettuce 1 44 Ast Trichoptilium incisum yellow-head V 45 Ast Trixis californica var. californica California trixis 1 46 Ast Volutaria tubuliflora *Mediterranean desert knapweed iN 47 Ast Xylorhiza orcuttii Orcutt's woody-aster V 48 Big Chilopsis linearis ssp. arcuata desert-willow V 49 Bor Amsinckia intermedia common fiddleneck iN 50 Bor Amsinckia tessellata var. tessellata bristly fiddleneck V 51 Bor Cryptantha angustifolia narrow-leaved cryptantha 99 52 Bor Cryptantha barbigera var. barbigera bearded cryptantha 1 53 Bor Cryptantha barbigera var. fergusoniae Santa Rosa Mountain bearded cryptantha iN 54 Bor Cryptantha costata ribbed cryptantha V 55 Bor Cryptantha ganderi Gander's cryptantha x 56 Bor Cryptantha maritima Guadalupe cryptantha 5 57 Bor Cryptantha micrantha var. micrantha red-root cryptantha V 58 Bor Cryptantha nevadensis var. nevadensis Nevada cryptantha x 59 Bor Cryptantha pterocarya wing-nut cryptantha x 60 Bor Emmenanthe penduliflora var. penduliflora whispering bells iN 61 Bor Eucrypta micrantha desert eucrypta iN 62 Bor Heliotropium curassavicum var. oculatum seaside heliotrope x 63 Bor Nama demissa var. demissa purple mat iN 64 Bor Pectocarya heterocarpa chuckwalla pectocarya 10 65 Bor Pectocarya peninsularis Baja pectocarya V 66 Bor Pectocarya platycarpa broad-fruited combseed 1 67 Bor Pectocarya recurvata curvenut combseed V 68 Bor Phacelia crenulata var. ambigua heliotrope phacelia 20 69 Bor Phacelia crenulata var. minutiflora little-flowered heliotrope phacelia 20 70 Bor Phacelia distans common phacelia 10 71 Bor Phacelia ivesiana Ives' phacelia iN 72 Bor Phacelia neglecta alkali phacelia iN 73 Bor Plagiobothrys jonesii Jones' popcorn flower iN 74 Bor Tiquilia palmeri Palmer's coldenia 1 75 Bor Tiquilia plicata plicate coldenia V 76 Bra Brassica tournefortii *Sahara mustard 99 77 Bra Caulanthus lasiophyllus California mustard iN 78 Bra Descurainia pinnata western tansy-mustard FC 79 Bra Dithyrea californica spectacle-pod 1 80 Bra Draba cuneifolia wedge-leaved draba iN 81 Bra Lepidium lasiocarpum ssp. lasiocarpum hairy-podded pepper-grass 99 82 Bra Sisymbrium irio *London rocket 5 83 Bra Streptanthella longirostris longbeak streptanthella 5 84 Bra Tropidocarpum gracile slender tropidocarpum iN 85 Bur Bursera microphylla elephant tree 13 86 Cac Cylindropuntia bigelovii teddy-bear cholla x 87 Cac Cylindropuntia echinocarpa silver cholla 22 88 Cac Cylindropuntia ganderi Gander's cholla 15 89 Cac Cylindropuntia ramosissima pencil cholla 20 90 Cac Echinocereus engelmannii Engelmann's hedgehog cactus 1 91 Cac Ferocactus cylindraceus California barrel cactus 8 92 Cac Mammillaria dioica California fish-hook cactus 1 93 Cac Opuntia basilaris var. basilaris beavertail cactus 1 94 Cam Nemacladus glanduliferus glandular nemacladus iN 95 Cam Nemacladus orientalis eastern glandular nemacladus iN 96 Car Achyronychia cooperi frost mat V 97 Che Allenrolfea occidentalis iodine-bush 99 98 Che Atriplex canescens var. laciniata Caleb four-wing saltbush 99 99 Che Atriplex elegans var. fasciculata wheelscale 10 100 Che Atriplex hymenelytra desert holly 3 101 Che Atriplex lentiformis ssp. lentiformis big saltbush 65 102 Che Atriplex polycarpa cattle saltbush 99 103 Che Monolepis nuttalliana Nuttall's poverty weed 99 104 Che Salsola paulsenii *Paulsen's Russian thistle 99 105 Che Suaeda nigra bush seepweed 99 106 Cle Cleomella obtusifolia Mojave cleomella iN 107 Cle Peritoma arborea bladderpod V 108 Cle Wislizenia refracta ssp. palmeri Palmer's jackass clover V 109 Con Cuscuta californica var. papillosa papillate dodder 3 110 Cra Crassula connata pygmy-weed FC 111 Cro Crossosoma bigelovii rock crossosoma V 112 Eup Chamaesyce micromera Sonoran spurge 1 113 Eup Chamaesyce polycarpa small-seeded spurge 80 114 Eup Chamaesyce setiloba starfish (Yuma) spurge V 115 Eup Croton californicus California croton 3 116 Eup Ditaxis lanceolata narrowleaf ditaxis x 117 Eup Ditaxis neomexicana New Mexico ditaxis V 118 Eup Stillingia spinulosa annual stillingia 20 119 Fab Acmispon strigosus strigose lotus 1 120 Fab Astragalus crotalariae Salton milk-vetch 99 121 Fab Astragalus didymocarpus var. dispermus dwarf white milk-vetch V 122 Fab Astragalus lentiginosus var. borreganus Borrego milk-vetch 99 123 Fab Dalea mollis silky dalea V 124 Fab Dalea mollissima downy dalea x 125 Fab Lupinus arizonicus Arizona lupine 23 126 Fab Lupinus shockleyi desert lupine iN 127 Fab Parkinsonia florida blue palo verde iN 128 Fab Prosopis glandulosa var. torreyana honey mesquite 99 129 Fab Psorothamnus emoryi Emory's indigo-bush 15 130 Fab Psorothamnus schottii indigo bush 50 131 Fab Psorothamnus spinosus smoke tree 1 132 Fab Senegalia greggii catclaw 20 133 Fou Fouquieria splendens ssp. splendens ocotillo 8 134 Ger Erodium cicutarium *redstem filaree 10 135 Ger Erodium texanum Texas filaree x 136 Kra Krameria bicolor white rhatany 40 137 Lam Hyptis emoryi desert-lavender 10 138 Lam Salvia columbariae chia 5 139 Lam Salvia vaseyi Vasey's sage 10 140 Loa Mentzelia affinis yellow blazing star 20 141 Loa Mentzelia desertorum desert blazing star V 142 Loa Mentzelia involucrata bracted blazing star 3 143 Loa Petalonyx thurberi ssp. thurberi Thurber's sandpaper-plant 10 144 Mal Eremalche exilis white mallow 1 145 Mal Eremalche rotundifolia desert five-spot V 146 Mal Hibiscus denudatus rock hibiscus x 147 Mal Malva parviflora *cheeseweed iN 148 Mal Sphaeralcea angustifolia copper globemallow 99 149 Mon Calyptridium monandrum sand cress iN 150 Mon Cistanthe ambigua dead man's fingers 99 151 Nyc Abronia villosa var. villosa hairy sand-verbena 50 152 Nyc Allionia incarnata var. incarnata small-flowered trailing four o'clock iN 153 Nyc Boerhavia triquetra var. intermedia fivewing spiderling iN 154 Nyc Mirabilis laevis var. retrorsa Bigelow's desert four-o'clock iN 155 Ona Camissoniopsis pallida ssp. pallida pale suncup iN 156 Ona Chylismia claviformis ssp. peirsonii brown-eyed primrose 99 157 Ona Eremothera boothii ssp. condensata Booth's evening primrose 7 158 Ona Eulobus californicus California suncup 99 159 Ona Oenothera deltoides ssp. deltoides dune primrose 99 160 Oro Orobanche cooperi Cooper's broomrape iN 161 Pap Eschscholzia minutiflora ssp. minutiflora small-flowered poppy x 162 Pap Eschscholzia parishii Parish's poppy x 163 Phr Mimulus bigelovii var. bigelovii Bigelow's monkeyflower x 164 Pla Mohavea confertiflora ghost flower V 165 Pla Plantago ovata desert plantain 99 166 Pol Aliciella latifolia ssp. latifolia broad-leaf gilia x 167 Pol Eriastrum eremicum ssp. eremicum desert woolly-star 5 168 Pol Eriastrum harwoodii Harwood's woolly-star iN 169 Pol Gilia stellata star gilia iN 170 Pol Langloisia setosissima ssp. setosissima bristly langloisia iN 171 Pol Linanthus jonesii Jones' linanthus iN 172 Pol Loeseliastrum matthewsii desert calico V 173 Pol Loeseliastrum schottii Schott's calico 99 174 Pol Chorizanthe brevicornu var. brevicornu brittle spineflower 3 175 Pol Chorizanthe corrugata wrinkled spineflower x 176 Pol Chorizanthe rigida devil's spineflower iN 177 Pol Eriogonum inflatum desert trumpet x 178 Pol Eriogonum thomasii Thomas' buckwheat x 179 Pol Eriogonum trichopes little desert trumpet 20 180 Pol Pterostegia drymarioides fairy bowties, threadstem iN 181 Res Oligomeris linifolia lineleaf whitepuff 99 182 Sim Simmondsia chinensis jojoba 20 183 Sol Lycium brevipes var. brevipes desert boxthorn 99 184 Sol Nicotiana clevelandii Cleveland's tobacco V 185 Tam Tamarix aphylla *athel 5 186 Tam Tamarix ramosissima *saltcedar 5 187 Vis Phoradendron californicum desert mistletoe 99 188 Zyg Fagonia laevis California fagonia x 189 Zyg Fagonia pachyacantha sticky fagonia x 190 Zyg Kallstroemia californica California caltrop iN 191 Zyg Larrea tridentata creosote bush 99 Monocots 192 Aga Hesperocallis undulata desert lily 50 193 Poa Aristida adscensionis six-weeks three-awn V 194 Poa Hilaria rigida big galleta 80 195 Poa Phalaris minor *little-seed canarygrass iN 196 Poa Schismus barbatus *Mediterranean schismus 99 197 Poa Stipa hymenoides Indian ricegrass iN
Voucher data provided by the participants of the Consortium of California Herbaria (ucjeps.berkeley.edu/consortium/)
Copyright © 2008-2020 by Tom Chester, Mike Crouse, RT and Shaun Hawke, Keir Morse, and John Randall.
Permission is freely granted to reproduce any or all of this page as long as credit is given to me at this source:
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Last update: 11 February 2020